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working on another WW2 style gun

John A.

Unconstitutional laws are not laws.
Staff member
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I have a good friend that bought one of the GSG/ATI mp40 clones in 9mm a while back that started out as a pistol. While he loved shooting it, he hated that he didn't have any way of shouldering the gun and it's really accurate considering you had to kind of just look over the gun while holding it out in front of you, so I started looking around at alternatives for him.

ATI sometimes sells a folding stock kit.

But, they're very proud of it apparently because they're between $200 and $269, and that's not even all that would be needed to do it legally. I didn't mention needing to add to the barrel (or another $200 to sbr the gun). Considering it's a metric barrel thread, that even further limits what's available.

So, I ordered a 12" piece of 3/4" rod. Hollowed it out so it would pass a bullet, and threaded it to 13mm to make the barrel extension to bring it to the legal 16" limit. After putting it in place and lathing the exterior into the diameter that I wanted, pinned and welded it. Of course, it got painted afterwards once the filing was done to make it as pretty as possible.

I had started to make a fake flash hider on it, but ultimately decided to just lathe it down to the same diameter as the rest of the portion beyond the barrel threads.


But, here's a pic of the underside after the welding and painting and such just in case anyone questions whether it was done right or not. It was.


Since he had no intention of spending $200 plus for a knockoff mp40 stock, I bought a demilled Pps-43 folding stock assembly to rob some of the parts to make this.


You're probably scratching your head wondering why, but there's an honest answer for that.

I only used the legs and the butt of it. Naturally, I couldn't use it the way it came. Well, duh!!! Because they're not the same kinds of guns.

The Pps-43 stock folded to the top, and the mp40 folded to the bottom, that meant that I had to grind the rivets out and take the butt off and flip it around the other way and also had to flip the legs too (the left on the right and the right on the left). I had to grind a lot of the locking piece to get the angle the way I wanted it so the butt would be the proper angle too.

Where I had to grind the rivets out, when I put it back together, I used #10-32 bolts. So, I literally had to completely take it apart and redo it entirely to be able to use it. Plus, demilled parts means exactly that too. So, that too should also count towards 922 from any way of looking at it. Plus, there's more parts to the assembly that were made in America too. He also bought a US made follower for it somewhere? So, that's enough parts to make it legal.

Sorry. No pictures of the new screws holding the butt on, but that was the only way to get it to look right on the mp40.

Removing the blocker thing on the receiver that ATI installed for import reasons was simple. But, making the internal portions to fit the shape of the gun was a chore. There's a few videos on youtube showing that step of the process from other people. You essentially drill or dremel the welds off of the blocker and remove the stock blocker things which are covering up the channel inside of there.

Below is a picture of the internal assembly I machined after I painted the exterior of the new assembly after I lathed it out. This is the portion that holds the stock legs to the receiver. There's actually 2 different threads that I used to do that. 1/4-20 through the center to join the two halves together and which tensions it down once it's placed through each side of the receiver to make it a solid piece. And if you haven't noticed, there are 5 different diameters to this part.


After the assembly was together, I put a small 10-32 bolt through the receiver as well to prevent it from folding.

Initially, I had considered doing a folding stock, but opted to just do a fixed, mainly because I think the grip portion is probably cast and I was unsure how much it would handle with the gun being pulled into the shoulder and recoil and stuff, so that's why I chose to just lock it in the open position. Which he said was perfectly fine with him. Either way, he's getting what he wanted and agreed that threading a big hole in the receiver that may crack on a part that will probably be terribly hard to replace if it did was a bad idea.

This pic below is before the legs and the butt was installed, but you can see the locking screw through the rear of the gun that keeps the internal parts from rotating.


I only have 2 more holes to drill and thread when my buddy comes back by so I can adjust the angle of the legs to get the proper height so his cheek lines up with the irons well. I'm fitting it to him specifically since he needs to be able to actually use it the way it was intended. You can see the hole that I already drilled through the leg so all I'll have to do is mark and drill it and thread it to lock the leg onto the assembly.


But, other than that, it's done and I just wanted to show off some of the work I did to convert it into a carbine for him. I enjoyed the project, but there was a lot of reverse engineering and measuring to make the various parts and to make them work. I don't know of anyone else who has went this route, but he paid about $55 for the buttstock and the aluminum rod for the various parts, so that's a heckuva lot better than what the importer is wanting for the stock assemblies. And should make it a lot more fun to shoot.

Don't know if that's how anyone else would describe it, but thanks for the compliment. It's just something that I enjoy doing.

I think of it more like a blind squirrel being able to find his own nuts occasionally.

This is probably one of those times LOL. I had never been inside of one of those before. And especially making anything for one. And very especially for using parts made for a different gun entirely to make pieces that I need. Reminds me a lot about Johnny Cash's Cadillac he put together one piece at a time.

If nothing else, it should be pretty solid and stable. I'd about bet a $10 bill that it'll have less movement than the adjustable stock ATI is selling. It's really stable. No wiggling or movement that I can determine from any direction. Which should be good. All I have to do is wait on him to swing by to check the cheek weld and drill and thread those two holes and it should be ready to go shoot. He said he was going to get some helium balloons filled up and tie a bunch to the target stands and give it a good run. I do admit that I'm looking forward to putting a couple of rounds through it to. You know. Just to check it. cough excuse cough.
Thanks buddy.

He had been asking about adding a scope rail on top of it and maybe adding a red dot sight. Since I'm not sure if it's made from aluminum or that cheap pot metal crap, I told him that while I could drill and tap it, I urged against it out of abundance of caution.

So, I did the next best thing that I could think of that I'm going to surprise him with today.

I drilled out the front sight and simply installed a red fiber optic rod in it.

My eye picks up on it fast. He'll never have to worry about his receiver cracking from adding a rail. Or, even needing to change batteries as long as there is some light available. While probably not as effective as an actual electronic dot since fiber optic doesn't work well at night, he probably wasn't going to use this as his first grab for HD anyway. So, its' use is likely going to just be 99.9999% fun range gun.


Thank you Ernst.

I'm blessed with good friends. I don't have hundreds of friends on facebook that I barely know like most people.

But, the friends I have, are true friends.

And I try to do right for and by them. Just like all the friends I have that have done things to help me out too. Especially when they did it out of the goodness of their heart.

We took the gun up to the range and shot it. He absolutely loved it. He was shooting those 4" square swingers very fast at 25 yards off hand and wasn't missing any. He was running the whole swinging tree without hesitation.

He loved the cheek weld. The extra support against his shoulder. The fiber front sight.

I shot it a few times, but didn't want to run through all his ammo. But, I could've shot that thing for a whole hour.
Nope not customer. I didn't ask for a penny for my time. He bought the parts of course, but it was raining so I didn't have anything better to do LOL
Yeah, I agree. I wouldn't mind owning it myself.

It would be a neat one to have, I think.
Thanks. I just enjoy doing stuff like this. It keeps me up and moving around. Albeit a lot slower than I once was LOL

He has shot the gun multiple times since I fooled with it, and he said he enjoys it a lot more now. He said it's more natural to shoot. And while it was accurate before, he said he thinks it's faster for him to switch between targets. Now, he's actually able to AIM the gun rather than just stick it out in front of him and POINT it in the right direction.

The mods have held up just fine and both of us believe that they'll stand the test of time. They're solid. He's had no issues with what I've done and has complimented it. That's ultimately all I was hoping for was to make it better for him.
…. So, that's enough parts to make it legal…..


I had to quit reading your post early on because there’s no way any of the stuff will be legal where I live.

One of the reasons I quit buying completely was that the guy I was buying from got busted for something like this. After that I couldn’t trust his judgment.
This is perfectly legal on a federal basis, and in my state.

No laws were broken in the making of this post.
I understand that entirely.

Here in California they can make anything they want illegal just by whining about it long enough.

But they know if they get rid of guns completely that the cartels will be taking over.